Method for treating a keratoconjunctival disorder

ABSTRACT

A method for treating a keratoconjunctival disorder, wherein the keratoconjunctival disorder comprises at least one disorder selected from the group consisting of a superficial punctate keratopathy, a corneal epithelial defect, corneal erosion, a corneal ulcer, a conjunctival epithelial defect, keratoconjunctivitis sicca, superior limbic keratoconjunctivitis, filamentary keratoconjunctivitis, keratitis and conjunctivitis, and wherein the method comprises orally administering from 3 mg/kg to 30 mg/kg per day of 2-phenyl-1,2-benzisoselenazol-3(2H)-one or a salt thereof to a patient in need thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of application Ser. No.11/920,477 filed Nov. 15, 2007 (U.S. Pat. No. 8,222,283), which is theUnited States national phase application under 35 USC 371 ofInternational application PCT/JP2006/309797 filed May 17, 2006. Theentire contents of each of application Ser. No. 11/920,477 andInternational application PCT/JP2006/309797 are hereby incorporated byreference herein.

TECHNICAL FIELD

The present invention relates to a preventive or therapeutic agent for akeratoconjunctival disorder such as dry eye, superficial punctatekeratopathy, corneal epithelial defects, corneal erosion, corneal ulcer,conjunctival epithelial defects, keratoconjunctivitis sicca, superiorlimbic keratoconjunctivitis, filamentary keratoconjunctivitis, keratitisor conjunctivitis, comprising 2-phenyl-1,2-benzisoselenazol-3(2H)-one ora salt thereof as an active ingredient.

BACKGROUND ART

Cornea is a transparent avascular tissue having a diameter of about 1 cmand a thickness of about 1 mm, while conjunctiva is a mucosal membranecovering the eyeball surface posterior to the corneal margin, and theback face of the eyelid. The cornea and the conjunctiva are known tosignificantly affect the visual function. Keratoconjunctival disorderscaused due to a variety of diseases such as corneal ulcer, keratitis,conjunctivitis and dry eye may adversely affect normal construction ofepithelium, and furthermore, may impair structures and functions of thecorneal stroma and endothelium, when the repair of these disorders isretarded, alternatively when these disorders are prolonged withoutmaking repair on some grounds. That is because the cornea and theconjunctiva are connected tissues. In these years, with the developmentof cell biology, factors participating in cell proliferation, migration,adhesion, extension, differentiation and the like had been elucidated,and it was reported that these factors play important roles in repair ofcorneal disorders (Japanese Review of Clinical Ophthalmology, 46,738-743 (1992), Ophthalmic Surgery, 5, 719-727 (1992)).

On the other hand, Proc. Natl. Acad. Sci. USA, 100 (13), 7919-7924(2003) describes that 2-phenyl-1,2-benzisoselenazol-3(2H)-one (genericname: ebselen, hereinafter referred to as “ebselen”) has an antioxidantactivity, and JP-A-2001-261555 describes that ebselen is effective as atherapeutic agent for cerebral arteriosclerosis and chronic cerebralcirculatory failure.

However, there is no report of study on a pharmacological effect of sucha compound on an eye disease such as a keratoconjunctival disorder.

DISCLOSURE OF THE INVENTION Problems to be Solved

It is an interesting subject to search a new medicinal use of ebselen.

Means of Solving Problems

The present inventors have made intensive studies in order to search anew medicinal use of the above-mentioned compound, and as a result, theyfound that the above-mentioned compound or a salt thereof exhibits anexcellent effect of preventing and improving a corneal damage in a testfor therapeutic effect using corneal disorder models and the like, andthus the present invention has been accomplished. Incidentally, the sametest was also carried out using known compounds having an antioxidanteffect similar to ebselen, however, ebselen exhibited a far superioreffect to these known compounds, which supports the excellent usefulnessof ebselen.

That is, the present invention is directed to a preventive ortherapeutic agent for a keratoconjunctival disorder such as dry eye,superficial punctate keratopathy, corneal epithelial defects, cornealerosion, corneal ulcer, conjunctival epithelial defects,keratoconjunctivitis sicca, superior limbic keratoconjunctivitis,filamentary keratoconjunctivitis, keratitis or conjunctivitis,comprising ebselen or a salt thereof as an active ingredient.

Ebselen of the present invention is a condensed heterocyclic compoundrepresented by the following chemical structural formula [I].

The salt of the above-mentioned compound is not particularly limited aslong as it is a pharmaceutically acceptable salt, and examples thereofinclude salts with an inorganic acid such as hydrochloric acid, nitricacid or sulfuric acid, salts with an organic acid such as acetic acid,fumaric acid, maleic acid, succinic acid or tartaric acid, and the like.Incidentally, the above-mentioned compound may be in a form of asolvate.

In the present invention, the keratoconjunctival disorder means thestate of damaged cornea and/or conjunctiva due to various causes such astear abnormality, metabolic abnormality and external damage, andexamples thereof include dry eye, superficial punctate keratopathy,corneal epithelial defects, corneal erosion, corneal ulcer, conjunctivalepithelial defects, keratoconjunctivitis sicca, superior limbickeratoconjunctivitis, filamentary keratoconjunctivitis, keratitis,conjunctivitis and the like. Further, dry eye as stated herein meandecreased tear production, xerophthalmia, tear deficiency, Sjogren'ssyndrome, keratoconjunctivitis sicca, Stevens-Johnson syndrome, lacrimalgland dysfunction, meibomian gland dysfunction, blepharitis, akeratoconjunctival disorder due to VDT (visual display terminal)operation, surgery, a drug, an external damage, use of contact lenses,etc., or symptoms accompanied by the keratoconjunctival disorder.

The preventive or therapeutic agent for a keratoconjunctival disorder ofthe present invention can be administered either orally or parenterally(instillation, transdermal administration or the like). Examples of thedosage form include eye drops, ophthalmic ointments, skin ointments,injections, tablets, capsules, granules, fine granules, powders and thelike. These can be prepared using any of widely used techniques. Forexample, the eye drop can be prepared using a tonicity agent such assodium chloride or concentrated glycerin, a buffer such as sodiumphosphate or sodium acetate, a surfactant such as polyoxyethylenesorbitan monooleate, polyoxyl 40 stearate or polyoxyethylenehydrogenated castor oil, a stabilizer such as sodium citrate or sodiumedetate, a preservative such as benzalkonium chloride or paraben asneeded. The pH of the eye drop is permitted as long as it falls withinthe range that is acceptable as an ophthalmic preparation, but ispreferably in the range of from 4 to 8.

The ophthalmic ointment can be prepared with a widely used vehicle suchas white soft paraffin or liquid paraffin. Oral preparations such astablets, capsules, granules, fine granules and powders can be preparedusing an extender such as lactose, crystalline cellulose, starch orvegetable oil, a lubricant such as magnesium stearate or talc, a bindersuch as hydroxypropyl cellulose or polyvinyl pyrrolidone, a disintegrantsuch as carboxymethyl cellulose calcium or low-substitutedhydroxypropylmethyl cellulose, a coating agent such ashydroxypropylmethyl cellulose, macrogol or a silicone resin, a filmforming agent such as gelatin film, and the like, as needed.

The present invention also relates to a method for preventing ortreating a keratoconjunctival disorder comprising administering apharmacologically effective amount of2-phenyl-1,2-benzisoselenazol-3(2H)-one or a salt thereof to a patient.

The dose of the above-mentioned compound can be properly selecteddepending on the symptoms, age, dosage form and the like. In the case ofan eye drop, it may be instilled once to several times a day at aconcentration of from 0.000001 to 1% (w/v), preferably from 0.0001 to0.1% (w/v). In the case of an oral preparation, it may be administeredonce or divided into several times at a dose of generally from 0.1 to5000 mg per day, preferably from 1 to 1000 mg per day.

Advantage of the Invention

As will be described below, when the following pharmacological test wascarried out, ebselen exhibits an excellent prevention and improvementeffect in corneal disorder models. Therefore ebselen is useful as apreventive or therapeutic agent for a keratoconjunctival disorder suchas dry eye, superficial punctate keratopathy, corneal epithelialdefects, corneal erosion, corneal ulcer, conjunctival epithelialdefects, keratoconjunctivitis sicca, superior limbickeratoconjunctivitis, filamentary keratoconjunctivitis, keratitis orconjunctivitis.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, results of a pharmacological test and preparation exampleswill be described, however, these examples are for understanding thepresent invention well, and are not meant to limit the scope of thepresent invention.

[Pharmacological Test]

1. Test for Therapeutic Effect on Corneal Damage Using Rats in which theExorbital Lacrimal Gland was Removed

Using male SD rats, corneal disorder models were produced in accordancewith the method of Fujihara et al. (Invest. Ophthalmol. Vis. Sci. 42(1): 96-100 (2001)). After the production of the corneal disordermodels, the improvement ratio of corneal damage was evaluated by amethod (Journal of the eye 21 (1): 87-90 (2004)) modified from themethod of Miyata et al. (Japanese Review of Clinical Ophthalmology 48(2): 183-188 (1994)).

(Test Method)

Male SD rats were systemically anesthetized by an administration ofNembutal. Subsequently, the exorbital lacrimal gland of each rat wasremoved and a corneal damage was induced over a period of 2 months.

Subsequently, ebselen was administered as follows. As comparativecompounds, 3-methyl-1-phenyl-2-pyrazolin-5-one represented by thefollowing formula [II] (hereinafter referred to as “edaravone”) and(3R)-1,2-dithiolane-3-pentanoic acid represented by the followingformula [III] (hereinafter referred to as “α-lipoic acid”) wereadministered as follows. Edaravone and α-lipoic acid are known to havean antioxidant effect (J. Radiat. Res., 45, 319-323 (2004), J. Nutr.,133, 3327-3330 (2003)). Ebselen also has the same effect as describedabove, therefore, ebselen, edaravone and α-lipoic acid are have a commonfeature in terms of having such an effect.

Ebselen Administration Group:

A physiological saline solution containing ebselen (25 μM) was instilledinto both eyes 6 times a day for 14 days (one group consisting of 8animals).

Edaravone Administration Group:

A physiological saline solution containing edaravone (200 μM) wasinstilled into both eyes 6 times a day for 14 days (one group consistingof 8 animals).

α-Lipoic Acid Administration Group:

A physiological saline solution containing α-lipoic acid (200 μM) wasinstilled into both eyes 6 times a day for 14 days (one group consistingof 8 animals).

In a control group, physiological saline was instilled into both eyes 6times a day for 14 days (one group consisting of 8 animals)

Fourteen days after the start of instillation, the damaged parts of thecornea were stained with fluorescein. For each of the upper, middle andlower parts of the cornea, the degree of fluorescein staining wasevaluated by scoring according to the criteria shown below and theimprovement ratio of corneal damage was calculated from the mean valueof the total scores for each of the above-mentioned parts.

(Evaluation Criteria)

0: No punctate staining

1: Scattered staining (punctate staining being separated)

2: Moderate staining (a part of punctate staining being adjacent)

3: Heavy staining (punctate staining being barely separated)

Incidentally, intermediate values (at intervals of 0.5) were set betweenthe respective scores.

(Results)

By taking the mean value of the scores for the control group(physiological saline) as a standard (improvement ratio: 0%) andaccording to the calculation equation shown below, the improvementratios for the ebselen (25 μM) administration group and the edaravone(200 μM) administration group and α-lipoic acid (200 μM) administrationgroup were calculated, respectively, which are shown in Table 1.Incidentally, the mean value of the scores is a mean of those of 8 casesin each group.Improvement ratio (%)={(control)−(administered compound)}/damagedegree×100Damage degree=(control)−(normal eye)

TABLE 1 Test group Improvement ratio (%) Ebselen (25 μM) administrationgroup 76.5 Edaravone (200 μM) 36.9 administration group α-Lipoic acid(200 μM) 30.8 administration group(Discussion)

As apparent from the results of the above-mentioned pharmacological testusing rats, ebselen exhibits a more remarkable improvement ratiocompared with edaravone and α-lipoic acid. In particular, it is asurprising result that ebselen exhibits an improvement ratio which ismore than twice as high as those of edaravone and α-lipoic acid althoughebselen was administered in an amount of one-eighth of the concentrationof edaravone and α-lipoic acid. Thus, it was shown that ebselen has aremarkable effect of improving a keratoconjunctival disorder.

2. Pharmacological Test Using SAMP10

Using senescence-accelerated mouse model P10 (hereinafter referred to asSAMP10), an effect of ebselen on a corneal damage was evaluated inaccordance with the method of Hirai, Shibagaki et al.(JP-A-2006-104913). Incidentally, as a control animal, SAMR1 with normalsenescence was used.

(Test Method)

SAMP10 develops a corneal disorder with aging. Accordingly, a cornealdamage of female SAMP10 at 16 weeks of age (before a change caused byaging is observed) was evaluated, and then, administration of an ebselensolution or its vehicle was started. At 8 weeks after the start ofadministration (at 24 weeks of age), the same evaluation was carried outagain. In the same manner, a corneal damage of female SAMR1 at 16 weeksof age was evaluated, and thereafter, administration of theabove-mentioned vehicle was started. Then, at 8 weeks after the start ofadministration (at 24 weeks of age), the same evaluation was carried outagain.

(Administration Method)

Ebselen suspensions obtained by suspending it in a 1% (w/v) methylcellulose aqueous solution (prepared by dissolving methyl cellulose inultrapure water) at a concentration of 0.45 mg/mL and 4.5 mg/mLrespectively were orally administered to female SAMP10 once a day at adose of 6.67 μL per g of body weight of mouse. The both administrationgroups were determined to be a 3 mg/kg group and a 30 mg/kg group,respectively. The administration was carried out 5 days a week (Mon,Tue, Wed, Thu, Fri) over a period of 8 weeks. As a control, a 1% (w/v)methyl cellulose aqueous solution was orally administered to SAMP10 inthe same manner at a dose of 6.67 μL per g of body weight of mouse.Further, to the control animal, female SAMR1, a 1% (w/v) methylcellulose aqueous solution was orally administered in the same manner.Incidentally, the number of animals in each group of SAMP10 is 22 eyes(11 mice), and the number of SAMR1 is 16 eyes (8 mice).

(Evaluation Method)

The damaged parts of the cornea of SAMP10 and SAMR1 were stained withfluorescein immediately before and at 8 weeks after the start ofadministration. For each of the upper, middle and lower parts of thecornea, the degree of fluorescein staining was evaluated by scoringaccording to the evaluation criteria described in “1. Test fortherapeutic effect on corneal damage using rat models in which theexorbital lacrimal gland was removed”, and the scoring of the degree ofcorneal damage (a maximum score of 9 points) was carried out byobtaining the total scores for each of the above-mentioned parts.

(Results)

The scores of fluorescein staining of SAMP10 and SAMR1 at 16 and 24weeks of age are shown in Table 2. Incidentally, the scores in the tableare expressed as mean±standard error in each group.

TABLE 2 Score of fluorescein staining Strain Administered agent 16 weeksof age 24 weeks of age SAMR1 Vehicle 2.44 ± 0.34 1.69 ± 0.31  SAMP10Vehicle 2.25 ± 0.22  4.23 ± 0.43** Ebselen 2.61 ± 0.38 2.95 ± 0.45* 3mg/kg Ebselen 2.45 ± 0.30 2.68 ± 0.33* 30 mg/kg **p < 0.01: Comparisonwith SAMR1 (Student's t-test) *p < 0.05: Comparison with the vehicleadministration group of SAMP10 (Dunnett's test)(Discussion)

As apparent from Table 2, at 16 weeks of age, there was no significantdifference between the vehicle administration group of SAMR1 and thevehicle administration group of SAMP10 (Student's t-test), and asignificant difference between the respective drug administration groupsof SAMP10 was not observed (Tukey test) either. At 24 weeks of age, itwas observed that the staining score is significantly increased in thevehicle administration group of SAMP10 compared with the vehicleadministration group of SAMR1. That is, it was confirmed that SAMP10develops a corneal disorder with aging. Under these conditions, it wasobserved that the staining score is significantly decreased in bothebselen administration groups of 3 mg/kg and 30 mg/kg compared with thevehicle administration group of SAMP10. That is, it was confirmed thatebselen has an effect of preventing and improving a corneal disorder.

PREPARATION EXAMPLES

Hereinafter, representative preparation examples using ebselen will beshown.

Preparation Example 1 Eye Drop

In 100 ml,

Ebselen  10 mg Sodium Chloride 900 mg Sterile purified water q.s.

By altering the amount of ebselen to be added, an eye drop at aconcentration of 0.001% (w/v), 0.03 (w/v), 0.1% (w/v), 0.3% (w/v) or1.06 (w/v) can be prepared.

Preparation Example 2 Eye Drop

In 100 ml,

Ebselen 100 mg Sodium Chloride 800 mg Disodium hydrogen phosphate 100 mgSodium dihydrogen phosphate q.s. Sterile purified water q.s.

By altering the amount of ebselen to be added, an eye drop at aconcentration of 0.05% (w/v), 0.3% (w/v), 0.5% (w/v) or 1% (w/v) can beprepared.

Preparation Example 3 Ophthalmic Ointment

In 100 g,

Ebselen  0.3 g Liquid paraffin 10.0 g White soft paraffin q.s.

By altering the amount of ebselen to be added, an ophthalmic ointment ata concentration of 1% (w/w) or 3% (w/w) can be prepared.

Preparation Example 4 Tablet

In 100 mg,

Ebselen   1 mg Lactose 66.4 mg  Cornstarch  20 mg Carboxymethylcellulose calcium   6 mg Hydroxypropyl cellulose   6 mg Magnesiumstearate 0.6 mg

Ebselen and lactose are mixed in a mixer, carboxymethyl cellulosecalcium and hydroxypropyl cellulose are added thereto, and the resultingmixture is granulated. The obtained granules are dried and the granulesize is selected. Then, magnesium stearate is added and mixed with thegranules with selected size and the resulting mixture is tableted with atableting machine. Further, by altering the amount of ebselen to beadded, a tablet with an ebselen content of 0.1 mg, 10 mg or 50 mg in 100mg can be prepared.

The invention claimed is:
 1. A method for treating a keratoconjunctivaldisorder, wherein the keratoconjunctival disorder comprises at least onedisorder selected from the group consisting of a superficial punctatekeratopathy, a corneal epithelial defect, corneal erosion, a cornealulcer, a conjunctival epithelial defect, keratoconjunctivitis sicca,superior limbic keratoconjunctivitis, filamentary keratoconjunctivitis,keratitis and conjunctivitis, and wherein the method comprises orallyadministering from 3 mg/kg to 30 mg/kg per day of2-phenyl-1,2-benzisoselenazol-3(2H)-one or a salt thereof to a patientin need thereof.
 2. The method of claim 1, wherein thekeratoconjunctival disorder comprises superficial punctate keratopathy.3. The method of claim 1, wherein the keratoconjunctival disordercomprises a corneal epithelial defect.
 4. The method of claim 1, whereinthe keratoconjunctival disorder comprises corneal erosion.
 5. The methodof claim 1, wherein the keratoconjunctival disorder comprises a cornealulcer.
 6. The method of claim 1, wherein the keratoconjunctival disordercomprises a conjunctival epithelial defect.
 7. The method of claim 1,wherein the keratoconjunctival disorder comprises keratoconjunctivitissicca.
 8. The method of claim 1, wherein the keratoconjunctival disordercomprises superior limbic keratoconjunctivitis.
 9. The method of claim1, wherein the keratoconjunctival disorder comprises filamentarykeratoconjunctivitis.
 10. The method of claim 1, wherein thekeratoconjunctival disorder comprises keratitis.
 11. The method of claim1, wherein the keratoconjunctival disorder comprises conjunctivitis.